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ServerSentEvent.scala
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ServerSentEvent.scala
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/*
* Copyright 2013 http4s.org
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.http4s
import cats.data.Chain
import fs2._
import fs2.text.utf8
import org.http4s.ServerSentEvent._
import org.http4s.util.Renderable
import org.http4s.util.Writer
import java.util.concurrent.TimeUnit
import java.util.regex.Pattern
import scala.concurrent.duration.FiniteDuration
import scala.util.Try
final case class ServerSentEvent(
data: Option[String] = None,
eventType: Option[String] = None,
id: Option[EventId] = None,
retry: Option[FiniteDuration] = None,
comment: Option[String] = None,
) extends Renderable {
def render(writer: Writer): writer.type = {
data.foreach(writer << "data: " << _ << "\n")
comment.foreach(writer << ": " << _ << "\n")
eventType.foreach(writer << "event: " << _ << "\n")
id match {
case None =>
case Some(EventId.reset) => writer << "id\n"
case Some(EventId(id)) => writer << "id: " << id << "\n"
}
retry.foreach(writer << "retry: " << _.toMillis << "\n")
writer << "\n"
}
override def toString: String =
s"ServerSentEvent($data,$eventType,$id,$retry)"
}
object ServerSentEvent {
val empty: ServerSentEvent = ServerSentEvent()
final case class EventId(value: String)
object EventId {
val reset: EventId = EventId("")
}
// Pattern instead of Regex, because Regex doesn't have split with limit. :(
private val FieldSeparator =
Pattern.compile(""": ?""")
def decoder[F[_]]: Pipe[F, Byte, ServerSentEvent] = {
case class LineBuffer(lines: Chain[String] = Chain.empty) {
def append(line: String): LineBuffer =
// val scrubbed = if (line.endsWith("\n")) line.dropRight(1) else line
copy(lines = lines :+ line)
def reify: Option[String] =
if (lines.nonEmpty) {
Some(lines.iterator.mkString("\n"))
} else
None
}
val emptyBuffer = LineBuffer()
def go(
dataBuffer: LineBuffer,
eventType: Option[String],
id: Option[EventId],
retry: Option[Long],
commentBuffer: LineBuffer,
stream: Stream[F, String],
): Pull[F, ServerSentEvent, Unit] = {
// def dispatch(h: Handle[F, String]): Pull[F, ServerSentEvent, Nothing] =
def dispatch(stream: Stream[F, String]): Pull[F, ServerSentEvent, Unit] = {
val sse = ServerSentEvent(
dataBuffer.reify,
eventType,
id,
retry.map(FiniteDuration(_, TimeUnit.MILLISECONDS)),
commentBuffer.reify,
)
Pull.output1(sse) >> go(emptyBuffer, None, None, None, emptyBuffer, stream)
}
def handleLine(
field: String,
value: String,
stream: Stream[F, String],
): Pull[F, ServerSentEvent, Unit] =
field match {
case "" =>
go(dataBuffer, eventType, id, retry, commentBuffer.append(value), stream)
case "event" =>
go(dataBuffer, Some(value), id, retry, commentBuffer, stream)
case "data" =>
go(dataBuffer.append(value), eventType, id, retry, commentBuffer, stream)
case "id" =>
val newId = EventId(value)
go(dataBuffer, eventType, Some(newId), retry, commentBuffer, stream)
case "retry" =>
val newRetry = Try(value.toLong).toOption.orElse(retry)
go(dataBuffer, eventType, id, newRetry, commentBuffer, stream)
case _ =>
go(dataBuffer, eventType, id, retry, commentBuffer, stream)
}
stream.pull.uncons1.flatMap {
case None =>
Pull.done
case Some(("", stream)) =>
dispatch(stream)
case Some((s, stream)) =>
(FieldSeparator.split(s, 2): @unchecked) match {
case Array(field, value) =>
handleLine(field, value, stream)
case Array(line) =>
handleLine(line, "", stream)
}
}
}
stream =>
go(
emptyBuffer,
None,
None,
None,
emptyBuffer,
stream.through(utf8.decode.andThen(text.lines)),
).stream
}
def encoder[F[_]]: Pipe[F, ServerSentEvent, Byte] =
_.map(_.renderString).through(utf8.encode)
}